a) Field of the Invention
This invention relates to compositions classified in the art of chemistry as new and novel peroxyoxalates of Structure A that are preparable by reaction of hydroxy-- ##STR2## [The definitions of Q, R.sup.1, R.sup.2, R.sup.3 and Z are given in the SUMMARY OF THE INVENTION]
hydroperoxides, such as 3-hydroxy-1,1-dimethylbutyl hydroperoxide and 3-hydroxy-1,1-dimethylpropyl hydroperoxide, with oxalyl halides and alkyl halooxalates, such as ethyl chlorooxalate, in the presence or absence of inorganic or organic bases, as well as processes for the preparation and use of the novel peroxyoxalates of Structure A. The peroxyoxalates of Structure A possess inherent applied use characteristics rendering them useful as reaction intermediates and as initiators for polymerizing ethylenically unsaturated monomers and for curing of unsaturated polyester resins.
There is a need in the polymer industries for efficient, free-radical initiators for polymerizing ethylenically unsaturated monomers at lower temperatures in order to attain higher molecular weight polymers having improved tensile and other mechanical properties and/or to increase rates of polymerizations in order to produce current polymers at higher rates of production. In the case of the latter scenario, the more efficient free-radical initiators enable polymer producers to increase productivity without need to build new and expensive production facilities. There also is a need in the polyester industry for free-radical initiators that cure unsaturated polyester resins faster and/or at lower temperatures. The inherent applied use characteristics of the new and novel peroxyoxalate compositions of Structure A of this invention are capable of satisfying these polymer industry needs.
b) Description of the Prior Art
P. D. Bartlett, et al. (J. Am. Chem. Soc., 82, 1762-8, 1960) described the decomposition kinetics of di-t-butyl diperoxyoxalate in solution and found its half-life at 60.degree. C. in benzene to be 6.8 minutes. In a subsequent paper P. D. Bartlett and R. E. Pincock (J. Am. Chem. Soc., 82, 1769-73, 1960) disclosed the decomposition kinetics of di-t-butyl diperoxyoxalate and several OO-t-butyl O-alkyl monoperoxyoxalates including OO-t-butyl O-ethyl monoperoxyoxalate and OO-t-butyl O-benzyl monoperoxyoxalate. Based on the data provided in this reference the 10 Hr half-life temperatures (i.e., the temperature at which 50% of the peroxide is decomposed in 10 hours) were calculated to be 26.degree. C., 39.degree. C. and 41.degree. C., respectively, for the above peroxyoxalates. Thus, di-t-alkyl diperoxyoxalates have 10 Hr half-life temperatures of about 25.degree. C. whereas OO-t-alkyl O-alkyl monoperoxyoxalates have 10 Hr half-life temperatures of about 40.degree. C. An OO-t-alkyl O-alkyl monoperoxyoxalate of the instant invention, i.e., O-ethyl OO-(3-ethoxycarbonylcarbonyloxy-1,1-dimethylbutyl) monoperoxyoxalate (I-1), ##STR3## was found to have a 10 Hr half-life temperature of 25.degree. C. in trichloroethylene. Hence, the novel OO-t-alkyl O-alkyl monoperoxyoxalates of the instant invention are significantly more active than the OO-t-alkyl O-alkyl monoperoxyoxalates of the art.
R. A. Sheldon and J. K. Kochi (J. Org. Chem., 35 1223-6, 1970) reported on the rates of decompositions of various di-t-alkyl diperoxyoxalates of the structure, ##STR4## (where R is methyl, ethyl, isopropyl and benzyl) The data were consistent with those of Bartlett.
W. Adams and J. Sanabia (J. Am. Chem. Soc., 99, 2735-9, 1977) describe the synthesis of a cyclic diperoxyoxalate, 7,7,10,10-tetramethyl-1,2,5,6-tetraoxa-3,4-dioxocyclodecane, from oxalyl chloride and 2,5-dimethyl-2,5-dihydroperoxyhexane in the presence of pyridine. Based on the data provided in this reference the 10 Hr half-life temperature of the cyclic diperoxyoxalate was calculated to be about 80.degree. C.
P. G. Griffiths, et. al. [J. Macromol. Sci., Chem., A17(1), 45-50, 1982] disclose polymerizations of alkyl methacrylates with di-t-butyl diperoxyoxalate (CAS RN 1876-22-2).
European Patent Application No. EP 0049966 A1 (Apr. 21, 1982, to ICI Australia, Ltd.) discloses a process for polymerizing vinyl chloride (VCl) monomer using as an initiator, di-t-butyl diperoxyoxalate.
M. Schulz, et. al. [J. Prakt. Chem., 324(4), 589-95, 1982] describe the synthesis and the thermolysis of azobis(isobutyl t-butyl peroxyoxalate), ##STR5## a sequentially decomposing azo-peroxide.
European Patent Application No. EP 0095860 A2 (Dec. 7, 1983, to ICI Australia, Ltd.) discloses a process for polymerizing VCl monomer using as an initiator a diester of monoperoxyoxalic acid of the structure, ##STR6## where R.sup.1 is a secondary or tertiary alkyl group, or a benzyl or a substituted benzyl group and R.sup.2 is a secondary or tertiary alkyl group, or a benzyl or a substituted benzyl group. Also disclosed in this patent application are t-alkylperoxy chlorooxalates of the structure, ##STR7## that are used for preparations of the diesters of monoperoxyoxalic acid.
U.S. Pat. No. 4,859,794 (Aug. 22, 1989, to Berol Nobel Nacka AB) discloses dialkyl esters of monoperoxyoxalic acid of structure, ##STR8## (where R=C.sub.4-10 t-alkyl and R.sub.1 =C.sub.18-28 primary alkyl) for example, OO-t-butyl O-docosyl monoperoxyoxalate, useful for initiating polymerization of VCl and other monomers.
Japanese Patent Applications JP 63/248806 (Oct. 17, 1988, to NOFCO) and JP 63/254110 (Oct. 20, 1988, to NOFCO) disclose OO-t-alkyl O-alkyl monoperoxyoxalates of the structure, ##STR9## [where R.sub.1 =H, alkyl and R.sub.2 =C.sub.1-7 alkyl, (substituted) C.sub.6 H.sub.5, etc.]
as initiators for producing VCl polymers having low odor and color.
European Patent Specification No. 0500624 B1 (Jul. 12, 1994, to Akzo Nobel N.V.) disclosed allyl peroxide chain transfer agents of the structure, ##STR10## where n is an integer of 1-4, R.sub.1 and R.sub.2 may be the same or different and are selected from hydrogen or lower alkyl, R.sub.3 is selected from alkyl of 4-8 carbons, alkenyl of 5-18 carbons, etc., X is an activating group capable of enhancing the reactivity of the olefinic unsaturation towards free-radical addition, m is 0 or 1 and Z is selected from the structures, ##STR11## If Z is the latter structure then the compounds of European Patent Specification No. 0500624 B1 can be monoperoxyoxalates. However, the compositions of 0500624 B1 do not disclose the compositions of the instant invention since the peroxides of Structure A are not allyl peroxides nor does the instant invention cover the compositions of 0500624 B.sub.1. It should be noted that no monoperoxyoxalates are included in the list of peroxides on pages 5, 7 and 8 or in the preparative examples of 0500624 B1.
As a whole, the above art does not disclose OO-t-alkyl O-alkyl peroxyoxalates which possess hydroxy, chlorocarbonyl-carbonyloxy, carboxycarbonyloxy or alkoxycarbonylcarbonyloxy groups on the OO-t-alkyl group such as in Structure A.
U.S. Pat. No. 3,236,872 (Feb. 22, 1966, to Laporte Chemical, Ltd.) discloses hydroxy-peroxides of the structure: ##STR12## (wherein R is a H, an acyl, an aroyl or alkyl group, especially the t-butyl group, t-amyl or the hexylene glycol residue; R' is an H or an acyl, aroyl or alkyl group.)
U.S. Pat. No. 4,525,308 (Jun. 25, 1985, to Pennwalt Corp.) and U.S. Pat. No. 4,634,753 (Jan. 6, 1987, to Pennwalt Corp.) disclose hydroxy-peroxyesters (above structure where R' is H and R is an acyl group) having 10 hour half-life temperatures below about 75.degree. C.
U.S. Pat. No. 3,853,957 (Dec. 10, 1974, to Pennwalt Corp.) discloses diperoxyketals and ketone peroxides containing hydroxy and acyloxy groups.
U.S. Pat. No. 3,671,651 (Jun. 20, 1972, to Pennwalt Corp.) discloses a hydroxy-peroxyester, t-butyl peroxy-3-hydroxypropionate, however, the product was difficult to prepare and, in addition, the substrate employed in the synthesis, i.e., .beta.-propiolactone, is a highly toxic cancer suspect agent.
U.S. Pat. No. 3,706,818 (Dec. 19, 1972, to Pennwalt Corp.) and U.S. Pat. No. 3,839,390 (Oct. 1, 1974, to Pennwalt Corp.) disclose sequential polyperoxides possessing peroxide moieties of differing structures and activities in the same molecule. The structures of this art do not anticipate the novel peroxyoxalates of Structure A.
c) Definitions
The 10 Hr half-life temperature of a free-radical initiator (e.g., an organic peroxide) is defined as the temperature at which half (50%) of the initiator decomposes in 10 hours.
In the instant invention, the monoperoxyoxalic acid, alkyl, t-alkyl esters Z, ##STR13## are named OO-t-alkyl O-alkyl monoperoxyoxalates. t-Cycloalkyl refers to the monoradical structure, ##STR14## where t is 0 to 2 and R.sup.x is a lower alkyl radical of 1 to 4 carbons, t-alkynyl is the monoradical structure, ##STR15## where R.sup.y is hydrogen or a lower alkyl radical of 1 to 4 carbons, and t-aralkyl is the monoradical structure, ##STR16## where R.sup.z is an aryl radical of 6 to 10 carbons.
When any generalized functional group or index, such as R, R.sup.1, R.sup.2, x, n, etc., appears more than once in a general formula or structure, the meaning of each is independent of one another.